Cellulose Flux Composition for Solder Void Suppression
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Solution Overview
Problem
Conventional fluxes struggle to effectively suppress the generation of various types of voids in solder joints, particularly in electronic components with different bonding areas, such as large QFN and small BGA or CSP, leading to decreased heat dissipation properties.
Innovation Solution
A flux containing massive cellulose, with fibrous cellulose fibers of varying lengths (1 μm to 1 mm and 1 nm to 1 μm), along with a solvent, rosin-based resin, and activator, is used to adjust viscosity and prevent void formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flux is used, then soldering process is simple, but voids of various sizes including champagne voids are generated in solder joints
Solution Approach 1:
The flux uses a composite thixotropic agent system combining organometallic compound and organic metal salt, creating synergistic effects that enhance void suppression capability while maintaining processability. This composite approach allows the flux to address multiple void types (large voids and champagne voids) simultaneously through coordinated chemical actions.
Solution Approach 2:
The invention optimizes specific parameter ranges: organometallic compound at 0.1-5 wt%, organic metal salt at 0.1-5 wt%, and controlled water content at 0.1-5 wt%. These parameter adjustments transform the flux properties to achieve optimal thixotropy and gas evolution control, enabling effective void suppression across different bonding areas.
2Reliability
If flux components are increased to suppress voids, then void suppression improves, but manufacturing cost and formulation complexity increase
Solution Approach 1:
The invention defines precise concentration ranges for each component (organometallic compound: 0.1-5 wt%, organic metal salt: 0.1-5 wt%, water: 0.1-5 wt%) to achieve optimal performance. These parameter specifications enable manufacturers to produce the flux with controlled complexity while ensuring consistent void suppression效果.
Solution Approach 2:
The flux formulation is designed to be universally effective across different electronic components (QFN with large bonding area, BGA/CSP with small bonding area) and void types (large voids and champagne voids). The multi-functional organometallic and organic metal salt combination provides broad-spectrum void suppression without requiring separate formulations for different applications.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The flux effectively suppresses the generation of various types of voids, including large and small champagne voids, across different soldering areas, enhancing heat dissipation and solderability.
Implementation Method 1
The flux of the present invention contains massive cellulose in which fibrous cellulose having a length of 1 μm or more and less than 1 mm and fibrous cellulose having a length of 1 nm or more and less than 1 μm are mixed
Data Source
AI summary
An aggregated cellulose is provided that includes massive cellulose and fibrous cellulose mixed together. The massive cellulose is fibrous and has a length of from 1 μm or more to less than 1 mm. The fibrous cellulose has a length of from 1 nm or more to less than 1 μm. The aggregated cellulose can contain from 400 ppm or more to 10,000 ppm or less of the massive cellulose. The aggregated cellulose can contain a solvent, a rosin-based resin, and an activator.